A developing cartridge including a developing roller is known in the art. The developing cartridge is attachable to and detachable from an image forming apparatus.
Prior art discloses a developing cartridge including a gear rotatable from a first position to a second position, and a protrusion provided at the gear. The protrusion is rotatable together with the gear, and contacts a lever provided at an image forming apparatus. The lever is moved by contact with the protrusion. The image forming apparatus detects the movement of the lever to determine a specification of the developing cartridge. Further, the gear includes a toothless portion. In a case where the toothless portion faces a drive gear configured to transmit driving force to the gear, meshing engagement between the gear and the drive gear is released, thereby causing rotation of the gear to be stopped. Thus, rotation of the protrusion is also stopped.